Reinforced Rocker Panel Two-Step Welding Process
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Solution Overview
Problem
Existing processes for forming reinforced rocker panels face challenges with internal stresses, deformations, and loss of structural integrity due to high strength steel materials, particularly when using patch type reinforcements, which can lead to reduced formability and bendability, especially in complex profiles like vehicle rocker panels.
Innovation Solution
A two-step welding process is employed, where a reinforcement patch is initially positioned in partial contact with a blank metal sheet, welded on one side of a predetermined bend line, bent, and then welded on the other side, reducing internal stresses and deformations by allowing improved workability and formability, and enabling the use of metal blanks with reduced gage thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If high strength steel materials (1300 MPa to 1900 MPa) are used to reduce vehicle weight while maintaining strength, then weight is reduced and strength is maintained, but material flatness, formability and bendability are reduced
Solution Approach 1:
The rocker panel is divided into multiple sections with different steel grades. High strength steel (1300-1900 MPa) is used in critical load-bearing areas to reduce weight, while lower strength steel with better formability is used in non-critical areas that require complex forming operations. This segmentation allows optimization of both weight and manufacturability across different regions of the component.
Solution Approach 2:
Different regions of the rocker panel are assigned different material properties (steel grades) based on their specific functional requirements. Critical structural areas receive high strength steel for weight reduction, while areas requiring complex bending and forming receive lower strength steel with superior formability characteristics.
2Strength
If patch type reinforcement is used to improve load transfer and stress distribution, then structural integrity is improved, but internal stresses and deformations increase during bending
Solution Approach 1:
The reinforcement patch is welded to the rocker panel portion before the cold forming operation. This preliminary welding establishes the structural connection in advance, allowing the subsequent forming process to create accurate geometric shapes without compromising the integrity of the weld joint or introducing excessive internal stresses.
Solution Approach 2:
The conventional sequence is inverted: instead of forming the rocker panel first and then adding reinforcement, the reinforcement is welded to the blank material before forming. This reversal allows the reinforcement to be integrated into the forming process, reducing differential stresses between the reinforcement and base material during bending.
3Strength
If reinforcement patch is welded before cold forming, then structural integrity is maintained, but material thinning and distortion increase
Solution Approach 1:
The welding parameters are specifically optimized for the high strength steel materials used in the reinforcement patch. By controlling welding variables such as heat input, welding speed, and electrode positioning, the process achieves strong joints while minimizing heat-affected zone distortion and material thinning during subsequent cold forming operations.
4Weight of moving object
If reduced gage thickness metal blanks are used to reduce weight, then weight is reduced, but formability and bendability are reduced
Solution Approach 1:
The rocker panel assembly is constructed as a composite structure combining thin-gage metal blanks with welded reinforcement patches. The thin-gage base material provides weight reduction, while the added reinforcement patches restore sufficient formability and bendability in critical areas, enabling complex shaping operations on otherwise too-thin material.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes internal stresses and deformations, enhances the structural and dimensional integrity of the rocker panel assembly, and improves the formability and bendability of the reinforcement patch, allowing for more efficient production of reinforced rocker panels with reduced material thinning and distortion.
Implementation Method 1
welding the reinforcement patch to the blank panel sheet
Implementation Method 2
bending the reinforcement patch and the blank panel sheet along the bend line
Data Source
AI summary
In a preferred embodiment, there is provided a process for forming a reinforced rocker panel assembly, and which includes positioning a reinforcement patch having first and second patch sections in surface-to-surface contact with a blank panel sheet, and welding the first patch section to the blank panel sheet. The process further includes bending both the blank panel sheet and the reinforcement patch along a bend line interposed between the first and second patch sections to form the blank panel sheet into a rocker panel portion having an elongated base section and a longitudinal flange, where the first and second patch sections are in at least partial abutting contact with the base section and the flange. The process also includes welding the second patch section to the flange.